This application claims the priority benefit of Taiwan application Ser. No. 88122148, filed Dec. 16, 1999.
1. Field of the Invention
The invention relates in general to a DVD-RAM disc. More particularly, this invention relates to rewritable DVD-RAM disc.
2. Description of the Related Art
One specification of the DVD-RAM version 2.0 disc has been provided in July, 1999. In this specification, the area and the parameters of the DVD-RAM have been defined. The specification includes a track pitch of 0.615 micron and a total capacity of 4.726 Giga-bytes. Referring to FIG. 1A and FIG. 1B, an area distribution of a conventional DVD-RAM disc is shown. In FIG. 1A and FIG. 1B, the DVD-RAM disc comprise a user area 14 of 4.7 Giga-bytes, a spare area of 146 Mega-bytes, a lead-in area 10 and a lead-out area 16.
The spare area 12 further comprises a main spare area 12 and a backup spare area. The main spare area 12 has a capacity of 26 Mega-bytes, and the backup spare area has a capacity of 120 Mega-bytes. The range of the backup spare area covers a portion of the last area (the 34th area) of the user area 14. That is, the backup spare area is included in the user area 14.
In a general operation, the user may use the above user area 14 only. There are two occasions to use the spare area for a user. One is when the DVD-RAM disc is produced and a quality inspection is performed to find out that the user area 14 is not writable. For example, as shown in FIG. 1C, the DVD tester automatically extends the user area 14 with an original compensation area 18 towards the main spare area 12. The dimension of the original compensation area 18 is equivalent to that of the original damage area 20. Therefore, to write the DVD-RAM disc, it starts from the original compensation area 18 and then enters the user area 14. While necessary, the original damage area 20 is skipped until the writing operation is complete.
The other occasion to use the spare area is when the user writes the DVD-RAM disc, the user area 14 is not writable. For example, as shown in FIG. 1D, when a damage area 24 occurs in the user area 14, the writing machine may obtain a compensation area 22 from the main spare area 12, and the compensation area 22 has a dimension the same as that of the damage area 24. Referring to FIG. 1D, when the writing machine writes along the direction that the arrow 102 points at and reaches the damage area 24, the writing machine then jumps to the in the compensation area 22 where the arrow 104 points at. After the compensation is written, the writing machine jump back to the user area 14 at the position that the arrow 106 points at and continues writing. The same steps are repeated until the writing is complete.
In the above two occasions, if the main spare area 12 is run out, the backup spare area 26 as shown in FIG. 1E is open, so that the coverage of the user area 14 is thus reduced.
In the prior technique, the total capacity of the main spare area 12 and the backup spare area 26 is 146 Mega-bytes. While the backup spare area 26 is open, the user area is reduced to 4.58 Giga-bytes. The ratio of the spare area to the user area 14 is 3.2% (146/4580=3.2%). Generally speaking, the ratio is too low for practical application since the spare area is easily run out.
The invention provides rewritable DVD-RAM disc. The location and dimension of the DVD-RAM disc is changed to enlarge the usable area. The enlarged area can be flexibly applied to the user area, the main spare area or the backup spare area.
The invention provides a rewritable DVD-RAM disc with a track pitch of 0.615 microns, and a diameter of 120 mm. The DVD-RAM disc comprises a lead-out area starting side and a lead-out area ending side. The lead-out area starting side is distant from a center of the DVD-RAM disc with a length of about 57.889 mm to about 58.145 mm. The lead-out area ending side is distant from the center of the DVD-RAM disc with a length of about 58.493 mm to about 58.516 mm.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.